Optical systems have many applications, including materials processing, sensing, illumination, and medical applications. Such optical systems often employ lasers, for example, fiber lasers, disk lasers, diode lasers, diode-pumped solid state lasers, and lamp-pumped solid state lasers. In these systems, optical power is often delivered by an optical fiber.
In some applications, it may be useful to vary optical beam characteristics (intensity distribution, divergence distribution, etc.), for example to optimize a process. Techniques to vary optical beam characteristics over time may facilitate realization of optimum beam characteristics, may facilitate rapid averaging or sweeping of the beam characteristics to provide beam smoothing via spatial averaging, and/or may result in speckle reduction. The optimum rate and amplitude of modulation, as well as the desired instantaneous and average beam characteristics, depend on the application. Most conventional lasers and optical systems including conventional lasers do not allow variation of a beam characteristic, particularly on short timescales. Free-space optics downstream from the laser could potentially provide some beam tuning capabilities, but such an approach entails significant cost, complexity, reduced reliability (sensitivity to contamination or misalignment of the optics), optical loss, and/or practical limitations (e.g., increased size and weight of process head, environmental sensitivity).
A fiber-based, or “all-fiber,” system for varying beam characteristics overcoming the limitations listed above would therefore be advantageous by eliminating one or more of the constraints associated with free-space optics.